This application is related to Japanese Patent Application No. 2000-142214 filed on May 15, 2000, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a heat exchanger in which a fluid flowing therein has a phase change with a heat exchange. The present invention is suitably used for an evaporator of a refrigerant cycle.
2. Description of Related Art
In a conventional evaporator described in U.S. Pat. No. 5,701,760, plural heat-exchanging portions are arranged in an air flowing direction, a separator is disposed at an approximate center position in each heat exchanging portion, and a downstream-air side lower tank is communicated with an upstream-air side upper tank through a communication path. However, when a flow amount (flow rate) of refrigerant flowing through the evaporator becomes smaller, liquid refrigerant flows in each heat exchanging portion to have approximately a distribution shown in FIG. 8A, and non-cooled portions A are overlapped in the air flowing direction as shown in FIG. 8B. Accordingly, in this case, temperature of air passing through the evaporator becomes nonuniform.
In view of the foregoing problems, it is an object of the present invention to provide a heat exchanger where a fluid flowing therein has a phase change by performing a heat exchange with air. In the heat exchanger, a temperature distribution of air passing through the heat exchanger can be made uniform even when a flow amount (flow rate) of refrigerant flowing through the heat exchanger is small.
According to the present invention, in a heat exchanger in which a fluid flows to have a phase-change by performing a heat exchange with air passing through the heat exchanger, the heat exchanger includes a plurality of tubes through which the fluid flows in a longitudinal direction of the tubes, a plurality first header tanks for distributing and supplying refrigerant into the tubes, each of which is disposed at one end side of each tube in the longitudinal direction, and a plurality of second header tanks for collecting refrigerant from the tubes, each of which is disposed at the remainder end side of each tube in the longitudinal direction. In this heat exchanger, the tubes and the first and second header tanks construct at least first through fourth heat-exchanging units for performing a heat exchange between fluid and air. Among the first through fourth heat-exchanging units, the first heat-exchanging unit and the second heat-exchanging unit are arranged in a line in a width direction approximately perpendicular to an air flowing direction, the third heat-exchanging unit and the fourth heat-exchanging unit are arranged in a line in the width direction, the first heat-exchanging unit and the fourth heat-exchanging unit are arranged in a line in the air flowing direction, and the second heat-exchanging unit and the third heat-exchanging unit are arranged in a line in the air flowing direction. In addition, the first through the fourth heat-exchanging units are disposed in such a manner that, a flow direction of fluid flowing through the tubes of the first heat-exchanging unit is opposite to that flowing through the tubes of the fourth heat-exchanging unit, the flow direction of fluid flowing through the tubes of the second heat-exchanging unit is opposite to that flowing through the tubes of the third heat-exchanging unit, the flow direction of fluid flowing in the first header tank of the first heat-exchanging unit is the same as that flowing in the first header tank of the fourth heat-exchanging unit, and the flow direction of fluid flowing in the first header tank of the second heat-exchanging unit is the same as that flowing in the first header tank of the third heat-exchanging unit. Accordingly, cool areas, where air is readily cooled, are symmetrical in the air flowing direction, the cool area is overlapped in the air flowing direction with an non-cooled area where air is hardly cooled, and it can prevent the non-cooled areas from being overlapped in the air flowing directions even when a flow amount (flow rate) of fluid is small in the heat exchanger.
Preferably, a fluid inlet is provided in the first heat-exchanging unit at a side adjacent to the second heat-exchanging unit, a fluid outlet is provided in the fourth heat-exchanging unit at a side adjacent to the third heat-exchanging unit, and the first through fourth heat-exchanging units are disposed in such a manner that refrigerant flows through the first heat-exchanging unit, the second heat-exchanging unit, the third heat-exchanging unit and the fourth heat exchanging unit, in this order. Accordingly, the structure of the heat exchanger can be made simple, and the dimension of the heat exchanger can be reduced.